In electrophotographic apparatuses using a xerography method such as a copier, a printer, and a facsimile apparatus, silicone rubber is sometimes used as the base materials of elastic body layers of elastic rolls such as a charging roll, a developing roll, a transfer roll, and a toner supply roll, a pressure roll, a fixing roll, and a paper feeding roll. The elastic body layers of the elastic rolls are required to have a low hardness, so that the silicone rubber that is the base materials may be foamed.